The pie 'tin' was probably aluminum - maybe sheet steel, if it was one of the robust types. Aluminum and acids usually react fast, with evolution of hydrogen.

The pie 'tin' was probably aluminum - maybe sheet steel, if it was one of the robust types. Aluminum and acids usually react fast, with evolution of hydrogen. I used to use that reaction to top off balloons (already partially inflated with air) with hydrogen. Tie off the balloon, touch a match - a satisfying kaboom!, with no shrapnel. My Mom was appalled. My Dad asked for do-overs.